OEM Lennox Contactor — 10F74

The genuine OEM Lennox 10F74 contactor is the electrically operated switch that energizes the compressor and condenser fan motor in your Lennox outdoor unit. When the thermostat calls for cooling, the 24-volt control circuit pulls in the contactor coil, closing the high-voltage contacts that deliver line power to start the compressor. It cycles thousands of times per season, making it one of the most wear-prone parts in the system.

A failing 10F74 is a leading cause of no-cool calls. Look for pitted, burned, or welded contacts, a loud buzzing or chattering at the unit, a compressor and fan that won't start (or won't shut off), or visible arcing and melted housing. Ants and debris lodged in the contacts are also a common cause of intermittent operation.

OEM matters because the contactor must match the correct coil voltage, pole configuration, and contact amperage rating for your Lennox unit's compressor load. An undersized or mismatched replacement can weld shut or fail prematurely under the inrush current. This factory-spec 10F74 ensures a proper electrical match and dependable, safe switching.